While ST has been one of my main factions over the last year, I do think think this interaction is a little questionable. I'm not sure how relevant it is throughout all of ladder because one could say that the setup and process is a little more difficult than average, but it's still easily done.
Setup two or three Orbs in the graveyard in the previous round, next round you play Oneiro/Royal Decree into Alzur which procs the Orbs. The result is he spawns two or three 6-cost units.
Now don't get me wrong, it's great that ST has another big play. My issue is with the way it resolves.
If you play Oneiromancy, this procs your two Orbs of Insight before you even search the deck for the card you want to play. So I'm curious as to why you are not forced to play them prior to playing the card you pick with Oneiromancy.
Same thing could be said about Necromancy proccing Orbs to flood the board with the 3 power engine.
With Alzur regularly pumping out an unanswerable 20+ points on Deploy, I can't see this interaction lasting forever, especially given the RNG nature of it. It's fun, but it easily makes him one of the strongest point slams in the game. I've had him come down for 30+ points plenty of times and have seen the same done to me. 25 points is not an uncommon Alzur deploy. Not bad for 11 provisions. Given that it rolls 3 separate times, the chance for a low roll is extremely low.